| Summary: | 碩士 === 國立嘉義大學 === 生物農業科技學系碩士班 === 100 === Abstract
Temperature stress is most serious limited factor for plant growth and development. As plant exposed to high temperature environment, the production of ROS were elevated and able to induce oxidative stress. In the commercial culture system, Phalaenopsis orchid is considered to be a temperature sensitive species, but few studies regarding the growth response of Phalaenopsis orchid to heat stress have been illustrated. The aim of this study is to determine whether different Phalaenopsis varieties would lead to varied response in high temperature environment. Heat stress effects on Phalaenopsis orchids were tested in 17 Phalaenopsis varieties with high degree of diversity in genetic background. Our results showed that Phalaenopsis varieties responded to high temperature differentially. Most tested varieties were tolerant to temperature of 32℃ by exhibiting stable chlorophyll contents and fluorescence values, and low ROS stress in this growth temperature. Our results indicated that hybrid plants derived from Phal. Doris and Phal. equestris parents were more tolerant to high temperature by exhibiting a low production of ROS compound and stable chlorophyll contents and chlorophyll fluorescence values in 37ºC growth temperature. In contrast, high levels of SOD and APX accumulation were found in the heat sensitive varieties which produced a higher amount of H2O2 at high temperature. In conclusion, different Phalaenopsis varieties exhibit different photosynthetic responses to heat stress due to genetic heterogeneity of breeding parents. Breeding of heat tolerant Phalaenopsis varieties is a good alternative to minimize the cost for cooling system during the high temperature seasons of greenhouse production.
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